Only my opinion but I read the adoption guidance as that the adopted child is still residing in their birth country and needs to return to the US with petitioner, as the petitioner does not reside in any other country.
It seems in your circumstances that you have already established a home with your adopted children in Canada, so I would not see an imminent need to leave, especially when it is a country like Canada. Financial strain and child care needs, I would not think, are top of the list for DCF, that's just life.
But again, only my opinion, I am not USCIS. Best thing you can do is ask. Worst that can happen is they say no. If they do, I don't think going back with a job offer would look shady.